Probiotic use may improve symptoms of depression

Regular intake of probiotics -- live bacteria and yeasts -- which are well known to be good for the digestive system may also relieve symptoms of depression, suggests a new study.

The findings revealed that twice as many adults with irritable bowel syndrome (IBS) reported improvement from co-existing depression when they took a specific probiotic than adults with IBS who took a placebo.

IBS affects the large intestine and patients suffer from abdominal pain and altered bowel habits like diarrhea and constipation. They are also frequently affected by chronic anxiety or depression.

"This study shows that consumption of a specific probiotic can improve both gut symptoms and psychological issues in IBS. This opens new avenues not only for the treatment of patients with functional bowel disorders but also for patients with primary psychiatric diseases," said Premysl Bercik, Associate Professor at McMaster University in Canada.

Further, the research showed the microbiota environment in the intestines are in direct communication with the brain, providing evidence that bacteria affects behaviour.

For the study, published in the journal Gastroenterology, the team involved 44 adults with IBS and mild to moderate anxiety or depression. 

They were followed for 10 weeks, as half took a daily dose of the probiotic Bifidobacterium longum NCC3001, while the others had a placebo.

At six weeks, 14 of 22, or 64 per cent of the patients taking the probiotic had decreased depression scores, compared to seven of 22 (or 32 per cent) of the patients given placebo.

Functional Magnetic Resonance Imaging (fMRI) showed that the improvement in depression scores was associated with changes in multiple brain areas involved in mood control, the researchers noted.